Field of the Disclosure
The present disclosure relates to a load control system for controlling a plurality of electrical loads and a plurality of motorized window treatments in a space, and more particularly, to a procedure for automatically controlling one or more motorized window treatments to prevent direct sun glare on work spaces in the space while minimizing occupant distractions.
Description of the Related Art
Motorized window treatments, such as, for example, motorized roller shades and draperies, provide for control of the amount of sunlight entering a space. Some prior art motorized window treatments have been automatically controlled in response to various inputs, such as daylight sensors and timeclocks. However, the automatic control algorithms of prior art motorized window treatments have resulted in frequent movement of the motorized window treatments, thus causing many distractions to occupants of the space.
Some prior art load control systems have automatically controlled one or more motorized window treatments to prevent sun glare while minimizing occupant distractions. For example, such a load control system may operate to limit the sunlight penetration distance in a space of a building. A system controller (e.g., a central controller) of the load control system may be configured to generate a timeclock schedule for controlling the motorized window treatments for limiting the sunlight penetration distance to a maximum penetration distance. The system controller may comprise an astronomical timeclock and may be configured to control the motorized window treatments according to the timeclock schedule to limit the sunlight penetration distance in the space.
Prior to execution of the timeclock schedule (e.g., at or before the beginning of each day), the system controller may be configured to analyze the position of the sun throughout the coming day on each façade of the building to determine the positions to which the motorized window treatments along a single façade must be controlled in order to prevent the sunlight penetration distance from exceeding the maximum penetration distance. The system controller may be configured to build the timeclock schedule to have a number of events throughout the day, such that the number of movements during each day does not exceed a maximum number of movements to minimize occupant distractions. The system controller may be configured to determine the positions to which to control the motorized window treatments on each façade at the event times of the timeclock procedure using the determined positions to which to control the motorized window treatments to prevent the sunlight penetration distance from exceeding the maximum penetration distance. Examples of load control systems for controlling motorized window treatments to limit the sunlight penetration distance in a space while minimizing occupant distractions are described in greater detail in commonly-assigned U.S. Pat. No. 8,288,981, issued Oct. 16, 2012, entitled METHOD OF AUTOMATICALLY CONTROLLING A MOTORIZED WINDOW TREATMENT WHILE MINIMIZING OCCUPANT DISTRACTIONS, the entire disclosure of which is hereby incorporated by reference.
Since the penetration distance in a space is dependent upon the position of the sun as well as an angle of the façade with respect to true north, all of the motorized window treatments along a single façade will typically be controlled to the same position by the system controller when executing the timeclock schedule. However, the motorized window treatments on adjacent facades that have different façade angles may be controlled to different positions. If the perimeter of a building is characterized by a number of façade angles, the motorized window treatments along the perimeter of the building may each be controlled to different positions, which may detract from the aesthetic appearance of the motorized window treatments in the building. In addition, some building have continuously curved facades, where the motorized window treatments located along the façade are each arranged at different angles. Accordingly, there is a need for a method of automatically controlling one or more motorized window treatments along a non-linear façade to prevent sun glare, while minimizing occupant distractions and maintaining alignment of adjacent motorized window treatments along the façade.